Mechanisms involved in liver damage resolution after hepatitis C virus clearance

Fibrosis regression following hepatitis C antiviral therapy

Hepatitis C virus (HCV) infection is one of the most common causes of liver pathology. It is a major etiological factor of continuous liver injury by triggering an uncontrolled inflammatory response, causing liver fibrosis and cirrhosis. Liver fibrosis is a dynamic process that can be reversible upon timely cessation of the injurious agent, which in cases of HCV is represented by the sustained virological response (SVR) following antiviral therapies. Direct-acting antiviral therapy has recently revolutionized HCV therapy and minimized complications. Liver fibrosis can be assessed with variable invasive and non-invasive methods, with certain limitations. Despite the broad validation of the diagnostic and prognostic value of non-invasive modalities of assessment of liver fibrosis in patients with HCV, the proper interpretation of liver stiffness measurement in patients after SVR remains unclear. It is also still a debate whether this regression is caused by the resolution of liver injury following treatment of HCV, rather than true fibrosis regression. Regression of liver fibrosis can possess a positive impact on patient's quality of life reducing the incidence of complications. However, fibrosis regression does not abolish the risk of developing hepatocellular carcinoma, which mandates regular screening of patients with advanced fibrosis.

Daclatasvir and Sofosbuvir Mitigate Hepatic Fibrosis Through Downregulation of TNF-α / NF-κB Signaling Pathway

BACKGROUND

Hepatic fibrosis is the major issue in chronic liver diseases such as chronic hepatitis C virus (HCV). The newly approved direct acting antiviral (DAA) agents such as Sofosbuvir (SOF) and daclatasvir (DAC) have been found to be associated with decreased fibrotic markers in HCV patients.

AIM

This study tried to explore whether the reported antifibrotic effect of these drugs is antiviral dependent or drug induced.

METHOD

Hepatic fibrosis was induced by (0.5ml/kg) CCl4 IP twice a week for six weeks. SOF (20 mg/kg/d) and DAC (30 mg/kg/d) were added in the last four weeks of treatments. Liver functions, fibrotic markers such as Hyaluronic acid and metalloproteinase-9 were detected using immunoassay. The expression of TNF-α/NF-κB signaling pathway as well as Bcl-2 were done using immunoassay.

RESULTS

SOF and DAC exerted a potent antifibrotic effect evidenced by their activity against hyaluronic acid HA and metalloproteinase MMP-9 significantly (P≤0.001). This effect was further proved histopathologically where liver tissues from rats treated by drugs showed marked inhibition of collagen precipitation as well as inhibition of HSCs activation. This antifibrotic action was associated with decreased expression of TNF-α /NF-κB signaling pathway and induction of Bcl-2.

CONCLUSION

SOF/ DAC antifibrotic effect is independent of its antiviral activity. The molecular events associated with this effect were the downregulation of TNF-α / NF-κB signaling pathway and induction of Bcl-2.

Mechanisms Underlying Hepatitis C Virus-Associated Hepatic Fibrosis

Hepatitis C virus (HCV) infection often causes liver diseases, including fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Liver fibrosis is the outcome of the wound healing response to tissue damage caused by chronic HCV infection. This process is characterized by the excessive accumulation of extracellular matrix (ECM) proteins, such as collagen fibers secreted by activated hepatic stellate cells (HSCs). Activation of HSCs from the quiescent stage is mediated by different mechanisms, including pro-inflammatory cytokines and chemokines released from HCV-infected hepatocytes and liver macrophages. HCV infection modulates the expression of different microRNAs that can be transported and delivered to the HSCs via exosomes released from infected cells, also leading to the development of advanced disease pathogenesis. Although recent advancements in direct-acting antiviral (DAA) treatment can efficiently control viremia, there are very few treatment strategies available that can be effective at preventing pathogenesis in advanced liver fibrosis or cirrhosis in patients. Assessment of fibrosis is considered to be the major part of proper patient care and decision making in clinical practice. In this review, we highlighted the current knowledge of molecular mechanisms responsible for the progression of liver fibrosis in chronically HCV-infected patients, and currently available methods for evaluation of fibrosis in patients. A detailed understanding of these aspects at the molecular level may contribute to the development of new therapies targeting HCV-related liver fibrosis.

Hepatoprotective influence of quercetin and ellagic acid on thioacetamide-induced hepatotoxicity in rats

Despite all the studies performed to date, therapy choices for liver injuries are very few. Therefore, the search for a new treatment that could safely and effectively block or reverse liver injuries remains a challenge. Quercetin (QR) and ellagic acid (EA) had potent antioxidant and anti-inflammatory activities. The current study aimed at evaluating the potential hepatoprotective influence of QR and EA against thioacetamide (TAA)-induced liver toxicity in rats and the underlying mechanism using silymarin as a reference drug. Fifty mature male rats were orally treated daily with EA and QR in separate groups for 45 consecutive days, and then were injected with TAA twice with 24 h intervals in the last 2 days of the experiment. Administration of TAA resulted in marked elevation of liver indices, alteration in oxidative stress parameters, and significant elevation in expression level of fibrosis-related genes (MMP9 and MMP2). Administration of QR and EA significantly attenuated the hepatic toxicity through reduction of liver biomarkers, improving the redox status of the tissue, as well as hampering the expression level of fibrosis-related genes. In this study, QR and EA were proved to attenuate the hepatotoxicity through their antioxidant, metal-chelating capacity, and anti-inflammatory effects.